# Start Time Missmatch - Analog vs. Digital channel in Raw export ?! **URL:** \ **Category:** Logic 2 Software\ **Created:** [June 30, 2025, 12:31pm UTC](https://discuss.saleae.com/t/start-time-missmatch-analog-vs-digital-channel-in-raw-export/3456 "2025-06-30T12:31:44Z")\ **Posts on this page:** 1\ **Showing post:** 3
**Author:** ![BitBob](https://yyz2.discourse-cdn.com/flex030/user_avatar/discuss.saleae.com/bitbob/32/2292_2.png) [@BitBob](https://discuss.saleae.com/u/BitBob)\ **Post date:** [July 1, 2025, 4:05pm UTC](https://discuss.saleae.com/t/start-time-missmatch-analog-vs-digital-channel-in-raw-export/3456/3 "2025-07-01T16:05:08Z")
See another post about analog filtering details: > [@Saleae Logic2 Analog filtering technical details?](https://discuss.saleae.com/t/saleae-logic2-analog-filtering-technical-details/2427/9): > > Hi @BitBob, I’m glad you’re interested! I’ve emailed you a copy of your device’s factory test data. You can try plotting that on a log/log graph to see that frequency response effect I was talking about, which is why we include a calibration filter in the calibration file. After reviewing your posts, I think I can cover all of your questions with the following background information. Why we don’t plan to add down sampling AA filters again for future analog products. To clarify, future analog … … specifically, about the **group delay** feature. You can look at your device-specific calibration file to see how your setup is calibrated. Ultimately, it is trying to ‘re-time’ the analog (filtered) data with the digital data streams due to extra latency caused by the various filters (hardware & software) and other delays (ADC sampling/conversion, etc.) Basically, a digital read is ‘faster’ and more ‘real-time’ than an analog reading. There is more signal processing hardware and post-processing software steps on the analog samples which will lag behind the timeline of the digital sample captures. Thus, a simple step function (i.e., change from 0V to 5V ‘instantly’) needs to be ‘synchronized’ between analog vs. digital display so they still appear to transition at the same ‘time’ in the waveform display (see `mGroupDelay` parameter in calibration file). I assume the ‘raw’ captured data is just the samples, without the group delay timing offset taken into account. Therefore, I suspect the meta data / start timestamps are needed to compare between channel timelines. --- _[View the full topic](https://discuss.saleae.com/t/start-time-missmatch-analog-vs-digital-channel-in-raw-export/3456)._